JPH05323659A - Electrostatic charge image developing toner - Google Patents

Abstract

PURPOSE:To impart long-term stable electrification property to toner particles and to obtain permanently good copy pictures by incorporating carboxylic acid into the surface of polymer resin particles and substituting a zinc salt for the carboxylic acid. CONSTITUTION:This electrostatic charge image developing toner consists of resin particles essentially consisting of a binder resin. In this toner, resin particles containing carboxylic acid at least on the surface of particles obtd. by dispersion polymn. method are used as the base particles, and the carboxylic acid is replaced by a zinc salt or the carboxylic acid is modified with a compd. having amino groups and sulfonate groups. Namely, by allowing a zinc compd. to react with the resin particles containing carboxylic acid obtd. by dispersion polymn., the carboxylic acid is changed into a zinc salt. In this case, the zinc compd. used is zinc chloride, etc., or a compd. expressed by formula may be adsorbed or diffused to the surface of resin particles. In formula, X is H, Li, Na or K atom, Y is a bivalent compd. having a skelton of 6-50C, and Z is H atom, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic charge image (electrostatic latent image) formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like.

[0002]

2. Description of the Related Art Generally, in an electrophotographic method or an electrostatic recording method, a developing sleeve is used to develop an electrostatic latent image formed on a latent image carrier made of a photoconductive photoconductor or a dielectric. A toner image that has been appropriately charged and made into a fine powder on a toner supply roller is transferred to a transfer material such as paper after development, and then fixed by heating pressure, solvent vapor, etc. Is obtained.

The developing methods applied to these electrophotographic methods and the like are roughly classified into a dry developing method and a wet developing method.
The former is further divided into a method using a two-component developer and a method using a one-component developer. Among the two-component developing methods, there are a magnet brush method using an iron powder carrier, a cascade method using a bead carrier, a fur brush method using a fur, etc., depending on the type of carrier that carries the toner.

Further, among the one-component developing methods,
Powder cloud method that uses toner particles in a spray state, contact development method (contact development or toner development) in which toner particles are brought into direct contact with the electrostatic latent image surface to develop, toner particles directly on the electrostatic latent image surface A jumping development method in which toner particles are charged and fly toward the latent image surface by the electric field of the electrostatic latent image without contact, a magnetic dry toner in which magnetic conductive toner is brought into contact with the electrostatic latent image surface to develop There are laws etc.

As the toner applied to these various developing methods, fine powder in which a colorant such as carbon black is dispersed in a binder resin made of natural resin or synthetic resin is used. For example, particles in which a colorant is dispersed in a binder resin such as polystyrene and finely pulverized to about 1 to 30 μm are used as toners. Further, a magnetic toner such as those containing a magnetic material such as magnetite is used as a magnetic toner.

As described above, the toner used in various developing methods has a positive or negative charge depending on the polarity of the electrostatic image to be developed. To retain the electric charge in the toner, it is possible to utilize the triboelectric charging property of the resin which is a component of the toner, but in this method, the toner charging property is small, so the image obtained by development is easily fogged and is not clear. In many cases, even if a sufficient amount of charge is obtained, rising of charge and deterioration of charge with time occur, and a satisfactory image cannot be obtained in many cases. Therefore,
Generally, in order to impart a desired triboelectric charging property to the toner, a dye, a pigment or a charge control agent which imparts the charging property is added.

Conventionally, as negative charge control agents, metal complex salts of monoazo dyes, nitrohumic acid and its salts, metal complexes of salicylic acid, naphthoic acid, dicarboxylic acids such as Co, Cr and Fe, sulfonated copper phthalocyanine pigments, There are nitro groups, halogen-introduced styrene oligomers, chlorinated paraffins, melamine resins, and the like, but these dyes have a complicated structure, the properties are not constant, and the stability is poor. Further, during thermal kneading, decomposition or mechanical shock, friction, changes in temperature and humidity conditions, and the like are likely to cause decomposition or deterioration, and a phenomenon in which charge controllability is deteriorated is likely to occur. Also, in many cases, the chargeability changes depending on the environment. Furthermore, when a conventional toner containing the charge control agent is used for a long time, filming may occur on the photoconductor due to poor charging.

Further, the dye / pigment or charge control agent added to these toners must be exposed to some extent on the toner surface in order to impart chargeability. Therefore, these additives fall off from the toner surface due to friction between toners, collision with a carrier, friction with an electrostatic latent image holding member, etc., and contamination of the carrier or the like, or electrostatic latent image holding member such as photosensitive Contamination of body belts or drums occurs. As a result, the charging property deteriorates, and the deterioration progresses as the number of durable sheets increases, the image density decreases, and fine line reproducibility and fog become problems in practical use.

Therefore, it has been attempted to improve the above-mentioned problems by improving the affinity and dispersibility of the binder resin of the toner and the dye / pigment or charge control agent which imparts the charging property. For example, there is a method of treating the surface of these additives in order to increase the affinity, but the surface treatment often lowers the charge imparting property. Further, in order to improve the dispersibility, there is also a method of increasing the mechanical shearing force to finely disperse it, but the proportion of the additive appearing on the toner surface decreases, and the chargeability tends not to be sufficiently imparted.

From these things, the additives for imparting the charge which are sufficiently satisfactory for practical use are very limited, and the number of practical additives is small. Further, in order to obtain not only a black-and-white image but also a color image, it is preferable that the one added to the toner is colorless, but most of the conventionally used dyes, pigments or charge control agents are dark colors. At present, there are few that have been put into practical use, and intensive research is continuing.

On the other hand, in recent years, in order to provide high image quality and high durability, there are demands for a smaller toner particle size, a sharp particle size distribution, sufficient coloring power, and uniform charge control.
That is, reducing the particle size of the toner improves quality such as resolution, sharpness, halftone reproducibility, and photographic reproducibility.
Further, when the particle size distribution is sharp, halftone reproducibility and photographic reproducibility are particularly improved. Further, even if the toner is used for a long time, the particle size distribution of the toner in the developer does not change, so that the stability of the image quality and the long life of the developer are brought about. for that reason,
Attention has been drawn to toners having resin particles obtained by dispersion polymerization or suspension polymerization and having a small particle size and a narrow particle size distribution as base particles.

However, in the case of a toner obtained by a dispersion polymerization method or a suspension polymerization method, since the manufacturing method thereof is greatly different from that of a kneading type toner, a new toner suitable for the toner charge control method is also suitable. Establishing a method is required. For example, after washing and drying the polymerized particles, it is attempted to dry mix the charge control agent with the polymerized particles and then drive it onto the surface of the polymerized particles, or dye the charge control agent used in the kneading method during the polymerization. ing.

[0013]

However, since the toner obtained by the implantation method does not sufficiently fix the charge control agent on the surface of the toner, there is a problem in quality over time, and it is difficult to put it into practical use. Further, when the charge control agent used in the kneading method is dyed, the charge control agent cannot be diffused into the inside of the polymer particles because of the large chemical structure of the charge control agent, and therefore, the sufficient charge control ability is obtained. It is the current situation that is not obtained.

Further, when the resin particles are prepared by the dispersion polymerization method, a polymer dispersant is generally used. Therefore, the polymer dispersant remains on the surface of the resin particles, and when the dispersion-polymerized particles are made into toner, the charging property is governed by the polymer dispersant remaining on the surface. When the surface on which the polymer dispersant remains is negative, a negative chargeability is obtained as a toner, but the rise of charge is poor and it is not sufficiently satisfied. Therefore, it is conceivable to attach a negative compound to the surface of the negatively-dispersed polymerized particles to impart negative charging property. However, due to a large ionic repulsion, such a method has a strong negative charging property. Cannot be given. On the other hand, when a positive property such as an ammonium salt is attached, the adhesion property is good on the negative surface, but the charging property is weak, and it is practically impossible to control the charging.

Therefore, an object of the present invention is to solve the above problems, that is, electrostatic charge image development which gives toner particles stable and appropriate chargeability for a long period of time and gives a good copy image permanently. To provide a toner for use.

[0016]

Means for Solving the Problems As a result of intensive studies, the present inventor has found that the surface of polymerized resin particles has a carboxylic acid,
Moreover, they have found that a toner in which the carboxylic acid is substituted with a zinc salt or a toner modified with a compound having an amino group and a sulfonic acid group are suitable for the above purpose, and have completed the present invention.

That is, according to the present invention, in an electrostatic charge image developing toner comprising resin particles containing a binder resin as a main component, the resin particles have a carboxylic acid on at least the surface thereof obtained by a dispersion polymerization method. Provided is a toner for developing an electrostatic charge image, which is a resin particle in which the carboxylic acid is substituted with a zinc salt.

Further, according to the present invention, in the toner for developing an electrostatic charge image comprising resin particles containing a binder resin as a main component, the resin particles have a carboxylic acid on at least the surface thereof obtained by a dispersion polymerization method. There is provided a toner for developing an electrostatic charge image, which is a resin particle and is obtained by adsorbing or sorbing a compound represented by the following general formula 1 on the surface of the resin particle.

## STR00001 ## XO ₃ S--Y--NZ ₂ (wherein, X, Y and Z are as follows.
X: H, Li, Na or K atom. Y: 6 to 50 carbon atoms
A divalent compound having the skeleton of Z: H atom or -CH ₃
Basis. )

The toner of the present invention can be charged with good quality by substituting a zinc salt for the carboxylic acid on the surface of the dispersion-polymerized resin particles or by modifying the carboxylic acid with a compound having an amino group and a sulfonic acid group. As a result, it has characteristics, and it is possible to obtain sufficiently satisfactory results in terms of charge rise, saturated charge amount, aging quality, and the like.

Hereinafter, the toner of the present invention will be described in detail. The toner of the present invention has, as a base particle, resin particles having a carboxylic acid on at least a surface obtained by a dispersion polymerization method, and the carboxylic acid is substituted with a zinc salt, or the carboxylic acid has an amino group and a sulfonic acid. It is modified with a compound having a group. In this case, the dispersion-polymerized resin particles having a carboxylic acid on at least the surface include, for example, a polymer material having a carboxylic acid group as a dispersant at the time of polymerization, and the resin itself constituting the resin particle has a carboxylic acid group And those having a compound having a carboxylic acid group attached to the surface of resin particles.

As described above, when the charge control agent is attached to the surface of the toner particles having the dispersion-polymerized resin particles as a base, for example, a negative compound is attached to the surface of the negative resin particles so that the negative charge property is reduced. Even if you try to give it, it is not possible to give a strong negative charging property probably because of a large ionic repulsion, and if you try to give a positive charging property by attaching a positive compound to the surface of the negative resin particles, The chargeability was good, but the chargeability was weak and it was virtually impossible to control the charge. However, as a result of the research conducted by the present inventors, at least the dispersion polymerized resin particles having a carboxylic acid on the surface thereof are reacted with a zinc compound to form a zinc salt of the carboxylic acid, whereby the above problems are solved and sufficient charge controllability is obtained. It was found that a toner having In this case, examples of the zinc compound used include, but are not limited to, zinc chloride and zinc sulfate.

Further, as a result of the research conducted by the present inventors, it was revealed that the counter ion to be reacted with the carboxylic acid may be other than Zn salt. That is, good charging characteristics can also be obtained by adsorbing or sorbing the compound represented by the following general formula 1 on the surface of the dispersion-polymerized resin particles.

## STR00001 ## XO ₃ S--Y--NZ ₂ (wherein, X, Y and Z are as follows.
X: H, Li, Na or K atom. Y: 6 to 50 carbon atoms
A divalent compound having the skeleton of Z: H atom or -CH ₃
Basis. )

More specifically, a compound represented by the above general formula 1 having at least an amino group and a sulfonic acid group in the molecular structure is adsorbed or sorbed on the surface of the dispersion-polymerized resin particles, The amino group present in the molecular structure of the compound and the carboxylic acid present on the surface of the dispersion-polymerized resin particles react to firmly fix the compound on the surface of the dispersion-polymerized resin particles. Further, sulfonic acid groups are present on the surface of the resin particles, and the sulfonic acid groups enable charge control.

Specific examples of the compound represented by the general formula 1 used in the present invention include those shown in Table 1 below, but are not limited thereto.

[0025]

[Table 1]

Examples of the monomer forming the binder resin used in the present invention include styrene, o-methylstyrene,
m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-
Styrenes such as nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene; ethylene, propylene, butylene, Ethylenically unsaturated monoolefins such as isobutylene, vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromine and vinyl fluoride; vinyl esters such as vinyl acetate and vinyl propionate; methyl acrylate;
Α-Methylene aliphatic monocarboxylic acid esters such as ethyl acrylate, -n-butyl acrylate, methyl methacrylate, ethyl methacrylate; vinyl ethers such as vinyl methyl ether; vinyl ketones such as vinyl methyl ketone; N-vinyl Examples thereof include N-vinyl compounds such as pyrrole, N-vinylcarbazole, N-vinylindole and N-vinylpyrrolidone. These monomers can be used alone or in combination of two or more kinds.

Further, as the monomer for forming the polycondensation type resin, ethylene glycol, triethylene glycol, 1,2-propylene glycol, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, poly Polyhydric alcohols such as oxypropylenated bisphenol A; polyhydric amines such as ethylenediamine, tetramethylenediamine, piperazine; maleic acid, fumaric acid, mesaconic acid, citraconic acid, adipic acid, malonic acid or their acid anhydrides or lower alcohols. Examples thereof include esters and the like. The present invention is not limited to the resin monomer shown here.

Additives such as colorants may be used in the toner of the present invention.
Metal black dyes such as oil black, nigrosine dye and metal-containing dye, aniline dye, chalco oil blue, chrome yellow, ultramarine blue, methylene blue chloride, phthalocyanine blue, rose bengal and other dyes or pigments are included.

If desired, the toner of the present invention may contain a fluidizing agent. For example, inorganic oxides such as SiO ₂ and TiO ₂ whose surfaces are made hydrophobic; inorganic fine particles such as SiC; A metal soap such as zinc stearate or the like can be used.

When the toner of the present invention is used as a two-component developer, it is used as a mixture with carrier powder. As the carrier in this case, all known carriers can be used, for example, iron powder, ferrite powder, magnetic powder such as nickel powder, glass beads, and those whose surface is treated with resin or the like. Can be mentioned.

[0031]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. The parts shown below are based on weight.

Example 1 First, base particles were manufactured by the dispersion polymerization method as follows.
That is, 320 parts of methanol was placed in a three-necked flask equipped with a stirring blade and a condenser, and the polymer dispersant Gantret was used.
(Copolymer of methyl vinyl ether and maleic anhydride:
6.4 parts of an average molecular weight of 40,000 was added little by little with stirring to completely dissolve it. Further, the following composition was added and completely dissolved. Styrene 25.6 parts n-Butyl methacrylate 6.4 parts 2,2'-Azobisisobutyronitrile 0.2 parts

While stirring these, the inside of the flask was purged with nitrogen gas and left for 1 hour. Polymerization was started while stirring at a stirring speed of 200 rpm in a constant temperature water bath of 60 ° C. ± 0.1 ° C. The liquid began to turn cloudy 15 minutes after heating. This liquid was a stable dispersion that became cloudy even after 20 hours of polymerization. Partial sampling and gas chromatography
As a result of measurement by the internal standard method, the polymerization rate is 92%
It was confirmed that

When the obtained dispersion was cooled and centrifuged at 2000 rpm in a centrifuge, the polymer particles were completely settled and the upper liquid was transparent. The supernatant was removed, 200 parts of methanol was newly added, and the mixture was stirred and washed for 1 hour.
The procedure of centrifuging and washing with methanol was repeated and filtered. The material separated by filtration was dried under reduced pressure at 50 ° C. for 24 hours to obtain styrene / n-butyl methacrylate copolymer particles as white powder in a yield of 95%. The obtained particles had a volume average particle diameter Dv = 5.50 μm. Also, Tg is 6
It was 3 ° C. [Hereinafter, these particles are referred to as polymerized particles (A). ]

Next, 1.0 part of Oil Black 803 (manufactured by Orient Chemical Co., Ltd.) was dissolved by heating in 200 parts of methanol, cooled, and filtered with a 1 μm filter to prepare a dye solution. Then, the polymer particles (A) are added to the filtrate 24 times.
Part of the mixture was added and dispersed, and the mixture was heated and stirred at 50 ° C. for 1 hour. Then, the dispersion liquid was cooled to room temperature and filtered to obtain colored resin particles, and the particles were again dispersed in methanol to obtain a colored resin particle dispersion liquid.

Next, zinc chloride was dissolved in ion-exchanged water, and 1.4 parts was added to 100 parts of the colored resin particles. 1
After stirring for a while, the mixture was filtered to obtain the toner of the present invention.

Example 2 First, a colored resin particle dispersion liquid was obtained in the same manner as in Example 1. Next, 0.1 part of a compound having a structure represented by the following formula 2 was dissolved in 100 parts of ion-exchanged water, and then 200 parts of the above colored resin particle dispersion liquid (particle concentration 30%) was mixed at room temperature. did. After stirring for 1 hour, the product was filtered and dried to obtain the toner of the present invention.

[Chemical 2]

Comparative Example In the same manner as in Example 1, colored resin particles were obtained without modification treatment with zinc oxide and used as a toner.

[0039]

[Evaluation Method] The toners obtained in the above Examples and Comparative Examples were mixed with a silicone resin-coated ferrite carrier (3 parts of toner, 100 parts of carrier), and imaged using a Ricoh copy machine Imagio 420. The toner was formed and the charging characteristics of the toner at that time were measured by the blow-off method. The results are shown in Table 2.

[0040]

[Table 2]

It can be seen from Table 2 that the toner of the present invention stably maintains an appropriate amount of charge for a long period of time. During the test, neither filming on the photoconductor nor spent on the carrier was observed.

[0042]

The toner for developing an electrostatic image of the present invention comprises resin particles containing a binder resin having a carboxylic acid on the surface, which is obtained by a dispersion polymerization method, as a main component, and the surface of the resin particles has a carboxyl group. Since the acid is replaced with a zinc salt, or the compound having an amino group and a sulfonic acid group is adsorbed or sorbed on the surface of the resin particles,
When an image is formed using this toner, good charging characteristics can be obtained stably over a long period of time, and the filming on the photoconductor and the phenomenon of spent on the carrier can be sufficiently suppressed. Is obtained.

Claims (2)

[Claims] 1. A toner for developing an electrostatic charge image comprising resin particles containing a binder resin as a main component, wherein the resin particles are resin particles having a carboxylic acid on at least the surface thereof, which are obtained by a dispersion polymerization method. Moreover, the electrostatic charge image developing toner is characterized in that the carboxylic acid is substituted with a zinc salt. 2. An electrostatic charge image developing toner comprising resin particles containing a binder resin as a main component, wherein the resin particles are resin particles having a carboxylic acid on at least the surface thereof, which are obtained by a dispersion polymerization method. Moreover, a toner for developing an electrostatic charge image, characterized in that the compound represented by the following general formula 1 is adsorbed or sorbed on the surface of the resin particles. ## STR00001 ## XO ₃ S--Y--NZ ₂ (wherein, X, Y and Z are as follows.
X: H, Li, Na or K atom. Y: 6 to 50 carbon atoms
A divalent compound having the skeleton of Z: H atom or -CH ₃
Basis. )